Hydrogen peroxide has a variety of uses in industry and medicine. Its manufacture in the U.S., since 1957, has been based primarily on the autoxidation of an anthraquinone. The anthraquinone (Riedl-Pfleiderer) process has been first commercialized by I. G. Farbenindustrie in Germany during World War II. All subsequent processes have retained the basic features of this process.
Essentially, a 2-alkylanthraquinone dissolved in a suitable solvent system is reduced catalytically to a corresponding anthraquinol (anthrahydroquinone). The anthraquinol is separated from the metal hydrogenation catalyst and aerated with an O.sub.2 containing air as to form the anthraquinone plus H.sub.3 O.sub.2. The H.sub.2 O.sub.2 is extracted with water, purified, and concentrated to the required degree. Yields are high but secondary reactions necessitate regeneration of the solutions and the metal catalyst on a regular basis.
Solvent systems for this process include 50:50 water and benzene, and a mixture of C.sub.7 -C.sub.9 alcohols, originally used in the Riedl-Pfleiderer process. Recent systems contain trialkylphosphates tetralkylated-substituted ureas, dialkycarboxylic acid amines and dicyclohexanes among other organic compounds.
The oxidation of alcohols in the presence of a photo-excited quinone has been discussed in an article by C. F Wells, "Hydrogen Transfer to Quinones", Transactions of the Faraday Society, 57, 1961, pp 1703 et seq. In a cylindrical quartz cell, a solution of isopropyl alcohol and sodium anthraquinone-2-sulfonate is shaken in the presence of oxygen while being irradiated by 365 nanometer light. The alcohol is oxidized to acetone, and hydrogen peroxide is formed. The oxygen uptake and the peroxide product have been measured to determine the reaction sequence.